This invention relates to an internal combustion engine whih has lubricating and liquid cooling systems and is provided with soundproofing cowling. More particularly it relates to the utilization of the lubricant and coolant as Soundproofing medias in the spaces between the engine and the cowling.
1. Field of the Invention
The addition of a soundproofing cowling to an internal combustion engine invariably produces higher wall temperatures and a corresponding increase in lubricant temperature. This is due to the inadequate exchange of heat between the outer surface of the engine and the environment. Provision must be made for the dissipation of this excess heat by some means such as an additional cooling system. It is the object of this invention to provide an internal combustion engine which has lubricating and liquid cooling systems with both adequate soundproofing and substantially improved cooling conditions.
2. Description of the Prior Art
The U.S. Pat. No. 3,601,101--Thien et al-- Aug. 24, 1971 and U.S. Pat. No. 3,693,602--Thien et al-- Sept. 26, 1972, each show an air cooled internal combustion engine which has a lower cowling enclosing the sump, and an intermediate cowling enclosing the crankcase, and an upper cowling enclosing the overhead value timing and fuel injection mechanisms. A cover is also provided for the value timing and fuel injection mechanisms. Cooling air is circulated through the spaces between the cowlings and the outerwalls of the sump, engine and cover.
Two types of liquid cooled internal combustion engines with soundproofing cowling means are shown in the U.S. Pat. No. 3,464,398--Scheiterlein et al-- Sept. 2, 1969 and U.S. Pat. No. 3,540,425--Scheiterlein et al-- Nov. 17, 1970 (Correspond to German Accepted Printed Applications (DAS) 1 751 124 and 1 775 468). The object of these internal combustion engines was exclusively directed to reducing the noise emanating from the internal combustion engine by suitably designing and shaping the cowling elements for enclosing the internal combustion engine. In both patents either an oil sump was fitted to the bottom end of the crankcase provided with openings, or an oil reservoir was fitted which projected considerably beyond the bottom end of the crankcase. This mode of accommodating the oil (required for lubricating the parts of the internal combustion engine) in a reservoir arranged underneath the crankcase presented the considerable disadvantage of restricting substantially the ground clearance of any vehicle equipped with an internal combustion engine of such design. On certain types of vehicles, for example earth-moving equipment, this is a factor causing considerable inconvenience, since such earthmoving equipment is frequently operated on uneven ground and thus often gets into an inclined position during its operation, so that the oil sump can easily be damaged. Furthermore, in this inclined operating position there is danger of the oil running to one side of the oil sump and of the lubrication pump drawing in air. When the machine takes up such an inclined position, there is also a chance of the crankshaft immersing in the oil which leads to undesirable losses do to splashing, because the oil is foamed up by the crankshaft and its lubricity decreases rapidly as a result of premature aging. Consequently, frequent oil changes are required. Finally, an oil sump fitted underneath the crankcase also presents a disadvantage inasmuch as the oil has to be drained off and the oil sump has to be dismounted before certain parts of the internal combustion engine can be removed. Ultimately, owing to their position underneath the crankcase the conventional oil sumps can take only a comparatively small quantity of oil which, in turn, necessitates intensive cooling of the oil by means of a cooling system.